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node Sofar( X : bool ) returns ( Sofar : bool );
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let
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Sofar = X -> X and pre Sofar;
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5
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tel
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node Abs( X : int ) returns ( Abs : int );
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let
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Abs = if X < 0 then -X else X;
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tel
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node excludes4( X1, X2, X3, X4 : bool ) returns ( excludes : bool );
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let
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excludes = not ( X1 and X2 or X1 and X3 or X1 and X4 or
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X2 and X3 or X2 and X4 or
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X3 and X4 );
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15
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tel
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node mesi(etat_me1, etat_me2, etat_me3, etat_me4 : bool
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) returns (
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modified_me, exclusive_me, shared_me, invalid_me : int
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);
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var
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garde_me1, garde_me2, garde_me3, garde_me4 : bool;
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let
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garde_me1 = pre invalid_me >= 1;
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garde_me2 = pre exclusive_me>=1;
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garde_me3 = pre shared_me>=1;
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garde_me4 = pre invalid_me>=1;
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modified_me = 0 ->
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if(etat_me1) then if(garde_me1) then 0 else pre modified_me else
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if(etat_me2) then if(garde_me2) then pre modified_me -1 else pre modified_me else
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if(etat_me3) then if(garde_me3) then 0 else pre modified_me else
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if(etat_me4) then if(garde_me4) then 0 else pre modified_me else
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pre modified_me;
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exclusive_me = 0 ->
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if(etat_me1) then if(garde_me1) then 0 else pre exclusive_me else
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if(etat_me2) then if(garde_me2) then pre exclusive_me -1 else pre exclusive_me else
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if(etat_me3) then if(garde_me3) then 1 else pre exclusive_me else
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if(etat_me4) then if(garde_me4) then 1 else pre exclusive_me else
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pre exclusive_me;
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shared_me = 0 ->
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if(etat_me1) then if(garde_me1) then pre shared_me -1+ pre exclusive_me +1+ pre modified_me - 1 else pre shared_me else
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if(etat_me2) then if(garde_me2) then pre shared_me else pre shared_me else
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if(etat_me3) then if(garde_me3) then 0 else pre shared_me else
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if(etat_me4) then if(garde_me4) then 0 else pre shared_me else
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pre shared_me;
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invalid_me = 3 ->
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if(etat_me1) then if(garde_me1) then pre invalid_me -1 else pre invalid_me else
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if(etat_me2) then if(garde_me2) then pre invalid_me else pre invalid_me else
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if(etat_me3) then if(garde_me3) then pre invalid_me + pre modified_me + pre exclusive_me + pre shared_me -1 else pre invalid_me else
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if(etat_me4) then if(garde_me4) then pre invalid_me + pre modified_me + pre exclusive_me + pre shared_me -1 else pre invalid_me else
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50
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pre invalid_me;
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tel
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node top( etat_me1, etat_me2, etat_me3, etat_me4 : bool ) returns ( OK : bool );
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--@ contract guarantees OK;
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var modified_me, exclusive_me, shared_me, invalid_me : int;
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env : bool;
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56
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let
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( modified_me, exclusive_me, shared_me, invalid_me ) =
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mesi( etat_me1, etat_me2, etat_me3, etat_me4 );
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env = Sofar( excludes4( etat_me1, etat_me2, etat_me3, etat_me4 ) );
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OK = env => (Abs(modified_me)+Abs(exclusive_me)+
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Abs(shared_me)+Abs(invalid_me)) <= 3;
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--%MAIN;
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--%PROPERTY OK=true;
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64
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tel
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